Electromagnetic clock



Feb. 24, 1925.

L.. H ATOT ELECTROMAGNETIC CLOCK Filed Feb. 13,'--1924 :sheets-sheet 1 Feb. 24, 1925. 1,527,255

L.. HATOT ELEGTROMAGNETIC CLOCK.

,n Filed Feb. 13, 1924 5 Sheets-Sheet 2 *e Feb. 24, 1925. 1,527,255

L. HATOT ELECTROMAGNETIC CLOCK Filed Feb. 13, 1924 3 Sheets-Sheet 5 CII Patented Feb. 24, 1925.

UNITED STATES LoN HA'roT, or PARIS, FRANCE.

ELECTR-OMAGNETIC CLOCK.

Application filed February 13, 1924. Serial No. 692,588.

T0 @ZZ whom it may concern:

Be it known that l', LoN Ha'ror, citizen of the French Republic, residing at 23 Rue de la Michodiere, Paris, France, have invented certain new and useful Improvements in Electromagnetic Clocks, ot which the following is a specification.

My invention relates to an electro-inagnetic clock comprising an operating pendulum of the known type wherein the circuitbreaker for the supply current which is mounted upon the pendulum device is closed for practically the whole et each successive swing of the pendulum in a given direction.

In this type of clock, the elements ot the electromagnetic system such as the perma` nent magnet and the current coil, are so disposed that the driving e'l'tort is exercised upon the pendulum during the whole time of closing ot the circuit. It the mechanical resistance ot the clockwork should increase, causing a corresponding diminution of the amplitude of oscillation, the counter-electromotive force induced in the solenoid by the motion of the said magnet will be diminished, and the operating` current becomes increased, thereby producing a greater power eiiiort which is constantly exercised for a like period, and this tends to restore the normal value of the oscillation.

But in order that this action should be effective and that the amplitude ot oscillation shall remain constant, the operating current must increase by a suiicient value. The current will however depend upon the diiierence between lthe E. M. F. ot the battery and the counter-emi which is induced, and the current variations due to the variations in the counter-emi. will be more apparent according as the counter-euri. is nearer the voltage of the battery. But in 'order to provide for a high value ot the counter-cant. it becomes necessary to employ magnets and solenoids or large size which are both cumbersome and expensive.

ln electric clocks of this type, it is turther required that the time of 'flow of the current shallbe exactly constant. The con-- tact arm which is mounted on the pendulum between two stop-pieces, one conducting and the other insulated, can he regulated in a, very exact manner for this purpose., and the said arm is given a considerable length and is pivoted at a distance. from the axis ol'; oscillation ot the pendulum; but in this ar 'angement the lever arm through which the mechanical resistance due to the said arm is caused to act upon the pendulum will have a great length, so that the resistance acting against the maintenance otl the oscillation will be also considerable.

My said invention has 'for its object to obviate the above-mentioned drawbacks and to provide for the construction of a clock or' small size at a reduced cost. It chieiiy consists in the use of an electromagnetic system wherein the power impulse is produced during a time which is much shorter than the duration of the electric current,

i. e. during the passage of the pendulum aujacent the vertical position. In this manner the specified time, which depends essentially upon the disposition of the electromagnetic system, will be exactly constant and hence the circuit-breaker is not required to open and close the circuit with any great precision.

For the circuit-breaker, l may employ a short and light arm which is mounted on the pendulum near its axis ot oscillation and which offers but a small mechanical resistance, and tiis will augment the coefficient of utilization of the electr ic power. I am enabled to provide an electromagnetic system which receives current during the entire pendulum stroke in a given direction but which develops power only adjacent the vertical position of the pendulum, this heing carried out by the use of a relativi-.ly fiat solenoid so disposed that the end of the magnet shall be engaged therein when the pendulum occupies the vertical position. la this arrangement, the flux in the i'nagnet which is surrounded by the turns ot' the solenoid will not vary appreciably except when the pele of the magnet passes through the solenoid. The electromagnetic effect is thus manifested as an impulse given to the pendulum when near the vertical posit-ion,

but it will be practically null during the i remainder of the stroke.

In this arrangement, the constant amplitude ot the pendulum is not obtained by variations in thev counter-einst. which as above stated must have. a great value in this 'f case, and for which poweriul elements ci" a large size must be employed, but l obtain the constant amplitude of oscillation by an electromagnetic action ot an antagonistic nature which is exercised upon the pendulum solely atthe end of its swing in order to insure the damping ot its motion, the

tl il action decreasing rapidly ywhen the ampli.- tude exceeds fthe norma-l value.

The damping or retarding device may consist of an energized solenoid whose polarity is contrary to that of the operating solenoid,

or be a. sliort-circuited solenoid, or again byY a. tube of non-magnetic ine-tal, and preterably of copper, the said solenoid or tube being so disposed that the end of the magnet shall be engaged -therein at the end of a stroke of normal amplitude.

By reason of this modification `of the regulating arrangement, and the bett-er use of the electric power, l am enabled to employ a very sho-rt pendulum comprising a light magnet, together with 'a weak solenoid,

' whereby clocks of very small size but of an accurate nature can be constructed. Due to the light weight of the pendulum, a suspension device can -be adopted consisting of loops of steel wire, this being simple as well as strong.V

Various constructional features rof an iinproved character', -intended either for the reduction of the mechanical resistance, or for simplifying the mechanism a-nd reduci-ng the cost, will he disclosed hereunder.

In this invention., I am chietly enabled to construct an electric clockmechanism whic-h is contained in a cylindrical case of the same size as those in current use tor mechanical clockwork, and which can he substituted for the latter upon t-he sai-ne clock bases.

A simple device for the `adjustment tor constant amplitude can v*be constructed by mounting below the pendulum magnet a second magnet whose inclination may be varied.

A construct-ional form of -a small clock in accordance with the invention 4is shown by way oit example in the appended drawings wherein:

F ig..1 is a section on a vertical dia-inetrical plane pass-ing through .the pivoting axis of the pendulum.

Fig. 2 is a front view ot' the mechanism, with the .dial removed.

Fig. 3 is an elevational view showing 'the battery and the elements for attaching the same as well as for the ready adjustment and transportation; the rear cover of thc clock is removed.

F ig. 4t is a transverse section on the line H of Fig. 3, showing in detail the manner in which the battery is :put in operation.

Fig. 5 is a detail section of Fig. 2 through line 5-5 showing on a large scale the suspension of the pendulum, the circuit-breaking element controlled :hY the pendu-lum. and the ratchet device controlling` the gearing which actuates the clock hands.

Fig. 6 is a section on the line i6 6 of Fig. 5.

Figs. 7 and 8 `show .two parts ot `the circuitebreaking element,

Fig. 9 isa view showingthe arrangement the operation of the suspension.

Fig. llsliowsa small clock comprising a base provid-ed with a cylindrical recess into which is fitted the cylindrical casing which contains all the elements of the clock-work as shown in Figs. 1 to 9 and upon whoseV bas is disposed a iegulating magnet.

The small clock comprises a cylindrical casing A whose front is constituted by the dial and which contains the clock mecha.- nism. Y

'The pendulum is shown in Figs. 1, 2, 5 and 6. It consists of a strip .of metal 1, pref" erably ot invar metal,rhaving at the lower end a magnet 2 in the torni of a circular arc whose centre coincides with the axis of motion of the pendulum; .the said magnet is secured to the strip 1 by the .clamping collar 3. The stri-p 1 is secured to a member 4t having .the form of aninverted VU by means of the Screw 5; the said screw also :maintains a loop 6 of a very hard steel vwire having the shape represented .on a large scale iin perspective Vin Fig. 9; said loop has the portions a; litt-ing exactly into holes in the strip 1, whereby it is well secured and will not move. To the `other end lof the member 4 is attached a tempered steel plate 7 by means of the screw 5k which also secures `a loop -6 similar to the loop f6. The loops `6 and -6 respectively engage two similar loops 8, 8 situated i-nja vertical `plane perpenclicular to the plane or" the loops s6, 6; the loops 8, 8 are held between two brackets 9, 9 by 4screws 10, 10; said brackets constitute the fixed support :of the pendulum, and are `secured to the plate 11 forming .the front of the casing A. The dial 12 is attached to said plate, the latter supporting all the elements lof the clock.

The movable arm ot the electric contact device, which is pivoted to the pendulum, consists of the screw 13, Figs. 5 and 6, having thereon a small ring of a precious nonrusting metal 14'; .the screw 13 is screwed linto a shaft 15 pivoting in apertures inthe member 4. At .one end Vof said shaft is mounted the pin 16 whereof the end is in contact with a spring strip 1T exercising a pressure in the direction of the axis of rotation; the other end of the shaft 1,5 is in Ycontact with -theplate 7, and shows a cavity l5', the shape of which is such that it 'will prevent llowing out of ythe lubricating oil disposed therein and thereby avoid excessive friction. Friction takes :place on 'the plate 7 .upon a relatively large dia-meter. A small spiral spring 17, Fig. 5, makes electric con- ,nectionbetween':the pendulum and 'the support 9;; the said spring is so disposed `that its centre line coincides with the asx-is of rotation of vthe pendulum, and it ollers vno.

disturbance to the operation, working under excellent conditions. Since the spring 17 bears upon the said shaft at a point at which the linear speed is null, there will be no friction nor alternation of the surfaces. A perfect electric connect-ion for the conducting arm is thus obtained by means of these various conditions.

The ring 14 is disposed between two small rods 18, 19, Fig. 6, secured respectively to the plates 20, 21 which are shown separately in Figs. 7 and S; said plates are mounted on a bracket 22 by the screws 23, 23. The rod 19 consists preferably of a precious nonrusting metal; the bracket 22 is attached to the base plate 11. The plate 20 is\electrical ly insulated by the insulating pieces 24, 24 and the insulating washers 25.

To the plate 11 is secured a solenoid 26, Fig. 2, comprising two coils 261, 262 connected in series but wound in the inverse direction; the coil 261 co-operates with one of the pole ends of the magnet 2 when the pendulum is in the vertical position.

The coil 261 has a relatively small height, this being such that when the Vpendulum makes its normal swing, the magnetic flux through the coil will not vary substantially except when near the vertical. Then the pendulum is at the end of the stroke in the direction of the arrow f, Fig. 2, the pole end will project out of the solenoid; the flux through the solenoid is equal to the flux in the magnet, and remains substantially independent of the angle of the pendulum when above a stated value (3 to 4 degrees in the case of the figure). In like manner, when the pendulum occupies the corresponding angular position on the other side of the vertical, and contrary to the arrow f, the. pole end will be entirely removed from the solenoid and the magnetic flux through the latter will be practically null. For this reason, when a current is sent through the solenoid during the whole stroke in the direction f, electro-magnetic energy will be produced solely when near the vertical. The coil 262 is disposed at the right of the coil 261 so that at small amplitudes the coil 262 shall be outside of the flux of the magnet.I and that this flux shall traverse. its wire turns only when the pendulum has moved sutilciently to the right. Further, one may dispose in symmetrical position on the other side of the vertical with reference to the coil 262, a short-circuited coil or simply a metallic tube 27 (preferably of good conducting electrolytic copper).

The source of current consists of a battery 28 placed in the rear of the casing A; the terminals 29, 30 of the battery are respectively connected to two spring strips 31, 32; said strips are secured to the base plate 11 and are electrically insulated. One end of the winding 261 and 262 is grounded in the frame and the other end is connected to the cont-act spring 31. The spring 32 is connected to the insulated plate 20.

During its motion lin tho direction the pendulum actuates a ratchet wheel 83, Fig. 6, by the pawl 34 mounted on a shaft 85 which is pivoted to the member 4 of the pendulum; the wheel 33 controls the clock hands A1, A2, A3 by means of suitable gearing, Fig. 1.

The operation is as follows:

At each stroke of the pendulum in the direction f, the conducting arm 13 comes into contact with the rod 19; this closes the circuit comprising the battery and the coils 261, 262 whereby a magneto-motive force is set up. The windings as well as the direction of the permanent flux of the magnet 2 are so calculated that this force shall have the direction of the mot-ion f, and that the electric energy shall exceed the opposing resistances.

In these conditions the amplitude of swing tends to increase, but the augmentation is limited by the action of the coil 26e and the tube 27; for large amplitudes, these latter will set up an antagonistic act-ion, thus providing for a very stable rate of working, as above indicated. This retarding action will be automatically eliminated if the amplitude should decrease by reason of the weakening of the battery or an increase in the friction. An excess of energy is thus available for the maintenance of the operation.

It will be observed that the pivot joint provided for the pendulum acts in the same manner as the knife-edge pivot of the known type in which the knife-edge is slightly rounded; this provides for a rolling motion without friction, Fig. 10. ln these conditions there will be no wear as takes place with the usual pivots. The arrangement indicated in the drawings (Figs. l, 2 and 7%) shows that all the elements are disposed so as-to occupy a small space'.

In order to modify the frequency of the oscillations and thus to advance or set back the clock, two arrangements have been provided:

1. A weight 36 movable on a rod 36 secured to the end of the pendulum, Fig. 1.

2. A stop-piece 37 which is mounted on the lever 3S (Fig. 2) pivoted at O and is urged by a spring strip 39 attached to the pendulum. By turning the lever 3S one can change the position of said stop-piece and hence modify the couple acting upon the pendulum due to the spring 39.

The battery 28 is secured to a plate 40 which is connected with the base plate 11 by the supports 41; the plate 40 has therein an aperture y), Figs. 1 and il, whose edges an, ay are raised so as to form a guide for the battery; the latter is held in place by an llt) arm 42 piyoting on an axle .45. To the plate 40 is pvoted ,an arm 43 .movable on an axle 44; the said ,arms serve -to hold the pendulum for transportation purposes, as shown in Fig. 3.

vThe clockwork can be protected by a glass disc 4G and Ia rear cover 47; themechanisin is secured tothe casing by hooks 44S, F ig. 3, turning upon the screws 49 which also serve to attach the plate 40 tothe supports 4l; the ends of said hooks engage in holes in the casing A. The coyer 4f( is secured in place solely by the springs 50, Fig. l, Yand it can be removed with great facility.

All `the complicated .parts are Vdisposed -betyveen the pla-tes ll and 40. The apentures 5l .and 52 are formed in the plate 4() Where.- by the regula-ting leyer 38 Aand the leyer 43 holding the pendulum can be operated tro-,1n the rear of the clock, after removing the cover 4 7, The battery 28 is set working .by iinply placing it in the position shown 4in 1e'- 4 It is observed that .all the elements are of a Snnnlc vand .substantial nature and can .be rcndily rcmcycd- To rc-mcy@ the mechanisni from the casing, it suilices to turn the hooks 48 the direction f3, Fig. 73, and to dran .ont thc plate 40;.al1t-ncclen1cntc will now vbe `quite accessible. An apparatus is thus .obtained Whichcan he manufactured in a snnnlc and .cccncnecal mennen A .device for magnetic regulation is shown by Way Off example which lServcc t0v adyancc or to set back the clock Without .interfering with the clockwork properly so `called, and it .consists essentially ,0f a magnet 5:5 .disposed vbelow the .cylindrical casing 56 containing all the elements of the 1clockwork and which Vis fitted into a corresponding round recess in a suitable base 5,7. The inagnet has st ibstantially the ,sanne length .as the pendulum mag-net 2; its poles S2 N2 lare situated respectively below vthe pendulum magnet poles N1 S1, ,and .exercise tl-ierfeupon, according to their vposition in like ,or .contrary pola-rit. l, la repulsion ,or an `attraction which modifies the .period of the oscillations. This action depends upon the spacing and the position of the magnet 55, and it is chieliy evident when kelnployu1g-a strong magnet 5,5 having a substantially horizontal position, wherein its .poles S2, N2 are res-pectively in the saine vertical line as the poles N 1 S1 When the pendulum is ,at rest. The .edect of said magnet upon the pendultnn @an 'be very slightly modified by givingv tothe Imagnet 55 a very k.sinall `inclination to the horizontal lin either direction, thereby setting .the clock forward or back. Forthis purpose, the -inagnet 5,5- is preferably :pivoted .at .one end to a shaft 58, Aand the .other end `Which v.serves as `a pointer, cooperates with .a graduated scale 60 indicating ,for instance i-n seconds per day the advance or retardation dne to a given position of the magnet- AIn this manner it .is feasible tc maintain the prcncl adinstnient zci the clock at vall til-nes', .in Spit@ of thc yarinticns cccnrng in .thc battery and .11h52 friction- Magnetif. rcgnlat-,icn has `already b ccn p11@- "idcd fnl electric clocks, whcncn a niece .cf soft iron is placed near the niagnet, said piece being disposed in the ,casingi 1 i a position in which it is not Snbicct to intenterence. l noyv substitute for said :iron piece a-pomyerjt'ul regulating magnet, and thev latter can be placed outside of the ,clocl case at .n ccitaindictnncc thc-reinem, Ac-,hllcfly aber@ thc ncndnhnn magnet-2,15 (as Shown) inn@- tically rectilinear, tor lin this event the action `of the magnet 55 on the magnet 2 will preserve its value in spite of a considerable Spacing nctwccn Said nnencts- .By .Snitabily separating lthe magnet 55 lfrom the penduhun magnet, it Lcan be mounted outside the clockwork case, in whdch Pesi-tion it .enables c Simple and .practical adinStmcn-tns Shown in Fig. l1.

What l claim S= l. An eleetlgornagneticl clock with motive pcndnlnnn comprising n Pcndulnln, n cn'- cnit-rbncakine clcmcnt lncunted neon .die Sad pcndnhnn and closing d1@ supply .ci-.1- cuit dior practically the entire y(duration of the successive swings of ,the .pe-ndi n in a einen .dlccticn an clcctnclnaencnc ...System consisting o :t a solenoid ,of sljnall lsize connected tc thc cnnnly circuit nnd by e lient magnet 0f Small Size, the Said magnet .1d-cine' mounted ,on the .pendu-loin .While the .said Sclcnc'd is disposed in -dlc Path cf thc Innsnct, .and :,lnccns Whcrcby thc' Said -clcctlfcmnenctc ,System shall act dn-01.1 'thc vpcndnlwfn only dur-ing a .time which is consi erably less than the ti-ne during which .the 1`circuit remains -clcccd a cclnnlcnlcntery 'elect-1nlnagnetic deyiee eXerC$i11-V a retarding' ayction nnen dac nendnlnnl -W` .cn at inc cn-d ci its ndnnal cwnls, and .Ineens idr fine-idly increasing ...the retanding action when the Y amplitude ,of swing increases.

2. An electromagnetic clock with motive Pendulum, 'comprising n pcndnnnn, n cnfcuit-,hrleaking element .mounted 7upon the Sa'd'perl-Clgull-Dn and closing .the supply cirf Vcuit :t'or .practically Ithe Ventire ,duration ot' the ,successive swings of the '.penduliun in a given direction., :an electroinagzgnetic-.systenuV consisting .of a .solenoid of .stn'allv size connected `to the ysupply circuit .and by ,a lig-.ht n lagnet of small size, .the said magnet being mounted on the pendulum lWhile the said Solenoid is ,disposed 'in v.the path of .the .inagnet, and ineens 4whereby the .said electromagnetic system shall act upon the .pendulum only duiging .a tilne .is Vconsiderably less than the Etime ,during Awhich the circuit remains closed, and devices `having an telectromagnetic retarding action, wherein the end of the magnct is placed when the pendulum is at the end of ifs swing of normal amplitude.

3. An electromagnetic clock with motive pendulum, comprising a suspended pendulum, a short and light circuit-breaking arm pivoted to the said pendulum very close to its suspension device, two stationary contacts one of which is included in the electric circuit and b-etween which the said arm is movable, a spring strip provided upon the pendulum and pressing against thel end of the pivoting shaft of the said arm, an electromagnetic system consisting of a solenoid of small size connected to the supply circuit and by a light magnet of small size, the said 'magnet being mounted on the pendulum Vwhile the said solenoid is disposed in the path of the magnetA and means whereby the said electromagnetic system shall act upon the pendulum only during a time which is considerably less than the time during which the circuit remains closed, a complementary electromagnetic device exercising a retarding action upon the pendulum when at the end of its normal swing, and means for rapidly increasing the retarding action when the. amplitude of swing increases.

4. An electromagnetic clock with motive pendulum, comprising a suspended pendulum, a short and light circuit-breaking arm, a pivoted shaft mounted on `said pendulum very close to its suspension device, a spring mounted on the pendulum which forms part of the electric circuit and urges the said shaft upon a very small front end surface of the latter, a bearing surface of relatively large area formed at the rear end of the said shaft, a recess formed in said pendulum and containing the rear end of the shaft, a contact surface provided in said recess and coacting with the rear end of ,theI shaft, an oil cavity formed in said rear end of the shaft, two stationary contact elements one of which is included in the electric circuit and between which the said arm is movable, a spring strip provided upon the pendulum and pressing against the end of the pivoting shaft of the said arm, an electromagnetic system consisting of a solenoid of small size connected to the supply circuit and by a light magnet of small size, the said magnet being mounted on the pendulum while the said solenoid is disposed in the path of the magnet, and means whereby the said electromagnetic system shall act upon the pendulum only during a time which is considerably less than the time during which the circuit remains closed, a complementary electromagnetic device exercising a retarding action upon the pendulum when at the end of its normal swing, and means for rapidly increasing the retarding action when the amplitude of swing increases.

5. An electromagnetic clock with operating pendulum, comprising a pendulum, loops of a very hard steel wire secured to the upper part of the pendulum and parallel to its plane of oscillation, similar loops of a very hard steel wire secured to thc clock frame perpendicular to the plane of oscillation of the pendulum, and engaging the first-mein tioned loops, a short an-d light circuit-breaking arm, a pivoted shaft mounted on said pendulum very close to its suspension device, a spring mounted on the pendulum which forms part of the electric circuit and urges the said shaft upon a lvery small front end surface of the latter, a bearing surface of relatively large area formed at the rear end of the said shaft, a recess formed in said pendulum and containing the rear end of the shaft, a contact surface provided in said recess and coacting with the rear end of the shaft, an oil cavity formed in said rear end of the shaft, two stationary contact elements one of which is included in the electric circuit and between which the said arm is movable, a spring strip provided upon the pendulum and pressing against the end of the pivoting shaft of the said arm, an electromagnetic system consisting of a solenoid of small size connected to the supply circuit and by a light magnet of small size, the said magnet being mounted on the pendulum while the said solenoid is disposed in th-e path of the magnet, and means whereby the lsaid electromagnetic system shall act upon the pendulum only during a time which is considerably less than the time during which the circuit remains closed, a complementary electromagnetic device exercising a retarding action upon the pendulum when at the end of its normal swing, and means for rapidly increasing the retarding action when the amplitude of swing increases.

6. An electromagnetic clock with operating pendulum, comprising a pendulum, loops of a very hard steel wire secured to the upper part of the pendulum and parallel to its plane of oscillation, similar loops of a very hard steel wire secured to thc clock frame perpendicularto the plane of oscilla-tion of the pendulum, and engaging the first-mentioned loops, a short and light circuit-breaking arm` a pivoted shaft mounted on said pendulum very close to its sus` pension device, a spring mounted cn the pendulum which forms part of the electric circuit and urges the said shaft upon a very small front end surface of thc latter, a bearing surface of relatively large area formed at the rear end of the said shaft, a recess formed in said pendulum and containing the rear end of the shaft, a contact surface provided in said recess and coacting with the rear end of the shaft, an oil cavity formed in said rear end of the shaft, two stationary contact elements one of which is included in the electric circuit and l be/tween Ywhich the saidlarm is movable, a

V-srnall size .connected to fthe supply circuit and Aby a light :magnet lof Smell size, the

said `lifglict being mounted on the pendulum livvhile `the said solenoid :is disposed -in the 4pat-li of the anagnet, -land means; Where- .by the Asaid electromagnetic system shall act upon the pendulum only during a time .which is considerably fless than the time during .which the circuit remains closed, a complementary Ielectrompag.11,etic A device eX- ercising la retarding action aipon .the @pendulum Awhen at the end its @normal saving, .and ,meansi .rapidly increasing the retard ing action Whenthe amplitudepfswinginlcreases, acylindricalcase Ymade l:in two por- .iQIlS whereof 011e @cation contains the ivhole of the above-mentioned ,elements, a uelockdial constituting the Afront aceof the said portion, the .second ,portion GQntaining :tivo electric contact ,strips constituting athe supply terminalaand .a removable ,batteryl avhose ltermina-ls cooperate with said :supply -fllvlilalS- 7,. electromagnetic vkclock with operating pendulum, Kcompri ing a pendulum, lloops ogt a. very lhard steel Wire secured fto the upper part of the pendulum and parallel to its pla-ne of oscillation similar loops of a yvery hard steel Wire secured to -the clock frameperpendicular to the plane otn oscillation of the fpendnhnn, and engaging the first-mentioned loops, `la short and flight ,circuit-breaking atm, a pivoted shatmounted .on said pendulum very icglose to itsl suspension device, a spring mounted on the pendulum which forms part of Ythe Velectric circuit and urgesthe Said :Sh-att npon a very small lfront end surface of the lat-ter, a bearing surface of relatively large area formed at the rear end of thel said shaft, .a recess formed in said pendulum and containing the rear `end of the shaft,` aconta-ct s-uriaee provided in said recess and coacting with the rear Aend of l,the shaft, .an oil -cawity lformed in said rear end of -the shaft,V tivo stationary contact elements one of Whichis included in the electriccircuit .and between which the Said arm is movable7 a spring strip tprovided Vupon the pendulum Aand Apressing against the end of the pivoting shaft of lthe said arm, an electromagnetic system consisting-of a solenoid of small rsize connected to the ysuppl-y circuit andV by `a whereof one portion contains the Whole of the above-mentioned elements, a clock dial constituting the front face of the sai-d portion, the second portion containing two elect-ric contact strips constituting the supply terminals, and a removable battery Whose terminals cooperate with said supply terminals, a base having therein a cylindrical recess cooperating in which is disposed the above-mentioned cylindrical case containing the clockwork, a regulating magnet disposed upon the saidbase below the said pendulum magnetV and having substantially the same length as the latter, a pivot shaft traversing oneend of the said regulatfng magnet7V the latter being movable upon the said pivot, means for securing the saidmagnetin each of its positions, and a graduated scale cooperating with the other end ofthe magnet.

vIn Witness whereof I have hereunto set my hand.

LoN naror. 

